Workers in highway work zones are exposed to risk of injury from the movement of construction vehicles and equipment within the work zones, as well as from passing motor vehicle traffic. Data from the Census of Fatal Occupational Injuries (CFOI) indicate that of the 841 work-related fatalities in the U.S. highway construction industry between 1992 and 1998, 465 (55%) were vehicle- or equipment-related incidents that occurred in a work zone. Highway workers routinely work in proximity to construction vehicles and motor vehicle traffic. Flaggers and other workers on foot are exposed to the risk of being struck by traffic vehicles or construction equipment if they are not visible to motorists or equipment operators. Workers who operate construction vehicles or equipment risk injury due to overturn, collision, or being caught in running equipment. Highway workers, regardless of their assigned task, work in conditions of low lighting, low visibility, and inclement weather, and may work in congested areas with exposure to high traffic volume and speeds. The Federal Highway Administration has developed and maintained the Manual on Uniform Traffic Control Devices (MUTCD), which provides for uniform design and setup of highway work zones. The primary focus of Part 6 of the MUTCD is the interaction between the road user and the work zone. The MUTCD contains exhaustive specifications for signage, pavement and curb markings, traffic signals, and marking of school zones, bicycle facilities, and highway-rail crossings. It also prescribes temporary traffic control measures for numerous scenarios involving lane closures, lane shifts, detours, shoulder work, median crossovers, mobile operations, and blasting. The MUTCD addresses topics such as training, personal protective equipment, speed reduction, barriers, and lighting, as they apply to highway construction. OSHA construction industry regulations (29 CFR 1926, Subpart O) address operation of vehicles and equipment within an off-highway job site not open to public traffic. However, Subpart O is not exhaustive in its coverage of machinery types or safety equipment, nor does it address work practices, traffic control plans, or shift work. Flagging and signaling practices are discussed in general terms in Subpart G, which covers signs, signals, and barricades. Subpart G defers to the 1971 MUTCD on matters relating to hand signals, barricades, and traffic control devices.